both fed the same signal from the JVC source using the same usb,
both feeding the very same 60rms helix speakers
both in the same car with the same interior
both rated 130rms (though helix b2 is actually rated 100rms its underrated and proven to be 138rms whereas the DLS RA20 is underated and 136rms )
both using everything identical
I find it hard to believe you would need to go to the above mentioned levels to make it a fair contest if everything is this identical with as much as a difference we heard anyway.
You need them to be very accurately level matched. The louder amp will usually be perceived as "better".
You also want to be able to switch back and forth instantly to hear differences immediately, not take an hour to swap stuff around and then try to remember and compare to your memory.
Yes, it makes a difference.